Rattail lebensspuren: Feeding impressions from deep-sea grenadiers

Abstract

Lebensspuren (‘life traces’) are biologically formed physical imprints or structures left behind in sediments, the origins of which are often unknown or speculative. During a biodiversity survey on Chatham Rise (a deepsea submarine ridge off SE Aotearoa New Zealand) in winter 2013, distinctive ‘iron-shaped’ lebensspuren, often with a central ‘bitemark’ where a plug of sediment had apparently been removed, were observed during towed camera transects at depths of 450–562 m. We link these impressions in soft deep-sea sediments to the head shape of grenadiers, and infer they resulted from grenadiers foraging on benthic prey. The imprints varied in shape, depth, and clarity. Two very clearly defined impressions were matched to Coelorinchus aspercephalus and C. biclinozonalis using ventral head profiles, and the size of the fish estimated. Grenadier foraging marks were frequently seen but their occurrence and densities have not yet been mapped.